1. Field of Invention
The present invention relates to chairs in general and in particular to a chair adapted to support and massage the back muscles of a user at one of a plurality of positions.
2. Description of Related Art
Chairs are common seating implements which commonly include a raised seating surface and a back rest or support. Chairs are used to support a user for working at a desk, table or the like or for relaxing. One common difficulty with conventional chairs is that their use may place stress or strain on the back of the user.
Stress or strain on the back of a user sitting in a chair may be due to the unnatural angles at which the back of the user is supported. Examples may be found in chairs that have backs which are too upright thereby forcing the user to support themselves at too steep of an angle of inclination or even vertically in some cases.
An additional source of stress or strain on the back of the user is due to the surface of the chair itself and the pressures it exerts upon the back of the user during use. In particular, many chairs include a hard surface. Such hard surfaces are known to cause pressure points leading to soreness and pain in the user. This is particularly the case the hard surface is rested against by the spine of the user.
Applicant is aware of previous attempts to provide a chair having a contact relieving portion in the middle of the back rest. Such attempts however have provided parallel panels which are rotatable or bend about a horizontal axis. In such devices however, the panels are often cantilevered from a bottom most portion and may therefore be prone to twisting about an axis parallel to the back of the user. Accordingly, such devices may upon application of pressure from the back of the user, be rotate about such an axis in a direction which reduces pressure of the panel on the muscles of the user adjacent to the spine. Examples of such devices may be found, in U.S. Pat. No. 5,577,811 to Ogg.